Escalator



Jan. 14, 1930. a. R. BARTLETT ESCALA'I'OR 2 Sheets-Sheet 1 Original Filed NOV. 15, I925 Jan. 14, 1930. 6. a. BARTLETT ESQALATOR Original Filed Nov. 15, 1925 2 SheetS-FSheet 2 Patented Jan. 14, 1930 UNITED STATES PATENT OFFICE ESCALATOR Application filed November 18, 1925. Serial No. 6 8,901.

This invention relates to a safety device for inclined conveyers and particularly to a safety device for escalators, either of the ascending or descending type.

The invention has for one of its objects to provide an escalator with a safety device whose operation is governed by the tension of the escalator chain. To this end, the safety device is provided with a movable member which is restrained from movement by the chain when the latter is under the proper tension for normal use, but which is permitted to be moved by a reduction in tension of saidchain to a predetermined point. The

i movable member co-operates with the chain to place the latter under the desired or normal tension, and also co-operates with other devices .to render them active to stop the escalator when the tension of the chain is reduced to a given or predetermined point.

The devices herein shown as governed by the movable member are a circuit controller and a brake mechanism, and said movable member is capable of effecting the operation of these devices either when the tension on the chain is reduced by elongation with the chain unbroken or when said tension is reduced to zero with the chain broken.

The movable member may also be utilized as a device for indicating wear of the chain as will be described.

These and other features of this invention will be pointed out in the claims at the end of this specification. 1 7

In the drawings illustrating the preferred embodimentof the invention, Figure 1 is a side elevation of a suflicient portion of an escalator embodying the present invention to enable the invention to be understood; Fig. 2

is a detail in elevation and section of the movable member shown in Fig. 1 and of parts associated therewith; Fig. 3 is a View similar to Fig. 2 showing the movable member in a different position; Fig. 4, is a plan View of the lower portion of the escalator shown in Fig.

1; Figs. 5 and 6 are diagrammatic details of a speed-controlling governor to be referred to; Fig. 7 is a detail in side elevation illus trating the preferred manner of'driving the governor; and Fig. 8 is a Wiring diagram ofthe circuits for controlling the motor and the motor brake. I

The escalator illustrated in the drawin may comprise any of the known constructions of escalatorsnow in use, and for purposes of illustrating thedifierent features of the present invention, the escalator may be. regarded as comprising an endless chain 10 adapted to travel over an upper sprocket '12 and a lower sprocket 13. The uppersprocket 12 is driven by a motor 14 represented in Fig. 8, the said sprocket being geared to the motor in the usual manner (not shown). The escalator chain 10 has operatively connected therewith tread members 15 which may be of any usual or preferred design and upon which the passengers stand in being conveyed from a lower to a higher level as in the case of an ascending escalator, or from a higher to a lowerlevel as in the case of a descending escalator.

In accordance with this invention, provision is made for stopping the escalator chain 10 when the tension on the chain is reduced to a predetermined point below the tension at which it is desired the chain should operate under normal conditions of use, and particularly when the tension on the chain is reduced to nothing as in case of chain breakage.

This feature of the invention is applicable to escalators of either the ascending or descending type, and as represented in Fig. 1, the invention is shown as embodied in an escalator of the descending type,wl1erein the lower sprocket 13 and its shaft 16 are arranged to be capable of being bodily moved in a downward direction under abnormal conditions of use, but which are restrained from such movement by the tension on the chain 10 under normal conditions of use.

This movement of the sprocket 13 is utilized in initiating the application of mechanism for bringing'the escalator chainto a stop.

In the preferred form of the invention, the shaft 16 upon which the lower sprocket 13 is mounted, is journaled to rotate in a movable carriage represented generally by the numeral 25, see Fig. 2, and comprising in the present instance side frames 26, 27 having at their front ends depending arms 28 .which are connected by a cross bar 29. The side frames 26, 27 are provided at their rear ends with boxes 30 for the shaft 16, which boxes are slidably mounted in longitudinal guideways formed by angle bars 31 secured to the main supporting frame 280 of the escalator. Each of the side frames 26, 27 is provided with a housing or casing 32 for a nut which is slidable but not rotatable therein. This nut is engaged with a threaded portion 34 of a rod 35, extended through one of the arms 28 and supported atits outer end by a cross bar 36 attached to the angle bars 31 and forming therewith the supporting frame for the carriage and its adjusting rods 35. Each adjusting rod 35 has mounted on it a helical spring 20, one end of which bears against the depending arm 28 and the other end against the nut 33 within the housing 32, the latter being provided at its. opposite ends with heads 38, 39 having openings for the passage of the adjusting rod 35.

Rotation of the adjusting rod 35 effects bodily movement of the nut 33 on said rod and compresses the spring 20 so as to cause it to move the carriage 25 and thereby place the escalator chain 10 under the desired tension for proper operation under normal conditions of use.

With the chain 10 under the desired tension, the nut 33 may abut against the front head 38 of its housing 32, and the spring 20 is compressed between said nut and the arm 28 of the carriage, as shown in Fig. 2. This leaves a space 40 between the nut 33 and the rear head 39 of the housing for movement of the carriage with relation to the nut.

This movement is permitted when the ten: sion on the chain is reduced to a predetermined point, which may be effected by elongation of the chain due to wear or by rupture of the chain.

Both adjustin rods 35 may be simultaneously rotated providing them with sprocket wheels 41 and connecting them by a link chain 42.

The movement of the carriage for the sprocket wheel 13 is utilized to effect the operation of other devices for stopping the escalator chain 10. These devices may be such as are now commonly used to stop the chain in case of breakage and in the present instance two such devices are illustrated. One device comprises a brake mechanism for J the shaft 16 of the sprocket wheell3, and

the other device is a circuit controller which governs the circuit of the electric motor employed to drive the chain and also a brake for said motor.

The brake mechanism for the shaft 16 of the lower sprocket wheel 13 comprises as herein shown, brake drums 44 fast on the shaft 16 at opposite ends thereof as shown in Fig. 4, and brake bands 45 cooperating therewith.

One end of each brake band 45 is connected to the cross bar 29 and the other end thereof is connected to the shorter arm 50 of a bell crank 51 pivoted upon a stud 52 upon the side frame of the movable carriage, and the longer arm of the bell crank 51 has cooperating with it a heavy coiled spring 54 to swing it from the position illustrated in Fig. 2 to that illustrated in Fig. 3, to tighten the brake band around the brake drum 44 when permitted to do so by latches 55, as will be described.

During the normal operation of the escalator, the longer arm of each bell crank 51 is locked in the position. illustrated in Fig. 2 by the latch 55, shown as a bell crank pivoted to a suitable support which may be the main supporting frame of the escalator and having its latching finger 56 yieldingly held in its locking position by a relatively heavy coiled spring 57 interposed between the latch and a fixed abutment 58, which may be a bracket upon the supporting frame of the escalator.

The shorter arm 59 of each bell crank is arranged to be engaged by a depending arm 60 on the carriage 25, so that when the carriage is moved downward a predetermined distance, the bell crank 55 will be turned to disengage the latching finger 56 from the brake lever 51 and thereby allow the spring 54 to apply the brake band 45 to the drum 44. Each bell crank 51 may be connected to a dash pot 61 supported by the carriage 25 and which functions to prevent rapid application of the brake band connected with it and serves to gradually bring the lower sprocket 13 and its shaft to a stop.

Under normal conditions of use, the brake band 45 is released from its drum 44 and is held in this position by the latch 55 as represented in Fig. 2.

Under such conditions, the chain 10 is placed under the desired tension to ensure proper operation of the escalator, by the spring 20. When, however, the tension on the chain is reduced to a predetermined point, namely to such point as will permit the carriage to trip the latch 55, the brake bands 45 will be applied to the drums 44 to stop rotation of the lower sprocket 13 and consequently stop the escalator chain.

The reduction in tension on the escalator chain may be caused by elongation of the chain due to wear or by rupture of the chain.

It will thus be seen that the escalator may be stopped with its chain 10 unbroken or when broken. The point to which the tension is reduced when the chain is broken is zero, and when the chain is unbroken, said point is one selected by the operator, and is governed by the tension-adjusting device, to wit:

the nut 33 and its housing 32.

By reference to Fig. 2, it will be seen that the nut 33 abuts against the head 38 of the housing 32 and that a maximum space 40 exists between the nut and the head 39 of the housing, which requires travel of the carriage equal tothe length of said space. 1

By adjusting the nut 33 on its rod 35 so as to diminish the distance between'it and the head 39 of its housing, the movement of the carriage necessary to release the brake lever 51 may be varied, and the point to which the tendslion on the-chain is reduced may be va-. r1e

It will therefore be seen that the point to which the tension on the chain is reduced, in order to permit the safety device to operate, may be varied at the will of the operator and therefore is determinable by him.

The movement of the housing 32 with relation to the nut 33 may also be utilized for indicating to an inspector the condition of the chain. This may be accomplished by providing the housing with a longitudinal slot 63 through which the position of the nut 33 with relation to the head 39 of the housing may be seen by the inspector, or a gauge mark may be placed onthe outsideof the housing and the relation of this mark to the nut 33 may be readily seen by the inspector.

1 Provision may and preferably will be made for stopping the rotation of the upper or driving sprocket 12 of the escalator when the tension on the chain is reduced to the predetermined point. To this end, a circuit controller is arranged with relation to the carriage so as to be held in a closed position during the normal operation of the escalator and to be opened when the carriage has been moved a predetermined distance.

The circuit controller is conventionally represented herein, see Figs. 2 and 3, and comprises contact members 7 0, 72 constructed and arranged 'to be maintained in contact until the carriage has been moved the predetermined distance, whereupon they are separated to. open the circuit in which they are included.

The contact members 70, 72 are shown in Fig. 8 as connected in amain circuit which includes the liolding coil 73 of a circuit breaker 74 of usual construction, and the armature 75 of the motor 14.

When, therefore, as will be apparent from an inspection of Fig. 8, the predetermined reduction in tension on the escalator chain occurs, a lug 71 on the arm of the carriage, which normally closes the circuit controller, permits the contact member to open the circuit of the circuit breaker 74, thus opening I the circuit of the motor 14 and cutting off the supply of current to the motor.

Included in the circuit leading from the circuit breaker 74 to the armature of the motor 14 is a solenoid 78, which during the normal operation. of the escalator and as long as the motor circuit is closed, holds a pair of pivoted brake shoes out of engagement with the brake drum 81 upon the motor shaft as diagrammaticall illustrated in Fig. 8.

When,,however, reakage of the escalator chain occurs or the tension on an unbroken chain is reduced to a predetermined point, the circuit breaker 74 is thrown to openposition and the solenoid 78 is deenergized, permitting the compressed springs 82 to cause the application of the brake shoes 80 to the motor shaft and thus stop rotation of the latter. In this manner the upper sprocket 12 and the upper portion of the broken escalator chain is held from movement by the co-opera tion of the brake shoes 80 with the brake drum 81.

If desired the circuit controller 70, 72 may be used also for controlling other devices, which may be employed for stopping the escalator. I

The present invention may-be used with an ascending or a descending type of escalator, and when used on the latter, it is preferred to include the circuit controller 70, 72 in a circuit controlling the motor 14 which includes another circuit controller which is operated by a governor driven by the motor, whereby provision is made for controlling an escalator of the descending type in the event that its speed should exceed a predetermined value, to the,end that injury to the passengers or the load may be prevented in the event that the escalator should run away.

For this purpose, the descending type of escalator may be provided with a governor operatively connected therewith and which may be of any usual type, the construction and mode of operation of which are well known, and represented in Figs. 5, 6 and 8 as comprising weights 102 connected by arms 103, 104 pivoted to fixed and movable sleeves or hubs 105, 106 respectively, upon the shaft 108.

The shaft 108 comprises the main rotatable shaft of the governor, and provision is made for rotating it in accordance with the speed of the escalator, and as herein shown through co-operating beveled gears 110, 112, a shaft 113 and co-operating beveled gears 114, 115, the latter being mounted upon the driving shaft 116 by which the escalator is driven from the motor through the usual connections (not shown).

The action of centrifugal force in throwing the weights 102 outwardly is restricted by a coiled spring 120 on the shaft 108, and

which is interposed between the fixed and movable hubs 105. 106 in the manner illustrated in Figs. 5, 6 and 8.

The movable hub 106 has connected therewith an arm 122 which co-operates with a plurality of circuit controllers 123, 124 controlling circuits to the field 125 and armagrammatically illustrated in Fig. 8, the speed of the motor is preferably controlled by shunting a resistance 130 which is normally in series with the field of the shunt motor 14. The resistance is so proportioned that under normal conditions of operation and at the normal speed of the motor, the latter operates upon a twenty per cent (20%) weakened field, and up to an over speed of the escalator amounting to twenty per cent (20%) of its normal speed the resistance 130 remains in series with the field of the motor.

\Vhen, however, the escalator speed reaches twenty per cent (20%) over speed, then a circuit is opened by a lug or projection 136 on the arm 122 moving out of engagement with the circuit controller 124, thus breaking a circuit between the controller 124 and its eo-o1')erating contact member 138, deenergizing a solenoid 140, permitting its arn'lature 142 to fall and close a circuit at the contacts 143, 144. which operates to shunt or shortcircuit the resistance 130, and consequently increase the strength of the field 125 to slow down the motor.

The governor moves the contact arm 122 in response to Variations in the speed of the escalator and causes the said contact arm to move into the position illustrated in Fig. 5, when the escalator reaches an over speed of twenty per cent (20%).

As the escalator slows down its speed, then the contact arm 122 is moved from the position illustrated in Fig. 5 to that illustrated in Fig. 8, whereupon the solenoid is again energized, breaking the shunt circuit at the contacts 143 and 144, and again interposing the resistance 130 into the field and enabling the motor to speed up.

In the event that the escalator should run away or increase in its speed to forty per cent (40%) above its normal speed, then the governor moves the arm 122 into the position illustrated in Fig. 6, in which a lug or projection l60 thereon is disengaged from the contact member 123, which leaves the contact member 148 and thereby not only cuts out the resistance 130 from the field 125, but also breaks a circuit between the contact member 123 and the contact 148.

The contact 148 is included in a' circuit from one side 150 of the main supply lines 150, 151 to the holding coil 73 of the circuit breaker 74 previously described, and when this circuit is opened. at the contact 148, then the holding coil 73 is deenergized, throwing the circuit breaker and opening the main circuit of the armature of the motor and also deenergizing the brake-holding solenoid 78, permitting the application of the brakes.

One embodiment of the invention is herein shown, but it is not desired to limit the invention to the particular construction shown.

Vhat is claimed is:

1. An escalator having in combination an endless conveyer member, means for driving said member under normal conditions of use, a brake mechanism co-operating with said conveyer member to arrest movement thereof indepernlently of said driving mechanism, means tor rendering said brake mechanism normally inactive under normal conditions of use, and means responsive to elongation of the endless conveyer member for rendering said brake mechanism active to arrest movement of the conveyor member independently of the driving mechanism under abnormal conditions of use.

2. An escalator having in combination an endless escalator chain, upper and lower sprockets around which said chain passes, means for supporting the lower sprocket to permit rotary and linear movement thereof, a brake drum operatively connected with said chain to be rotated thereby under normal conditions of use, a brake band co-operating with said brake drum, means for rendering the brake band inactive under normal conditions of use, and means responsive to linear movement of the supporting means for the lower sprocket for rendering the brake band active to arrest rotation of the brake drum and movement of the said chain under abnormal conditions of use.

3. An escalator having in combination an endless conveyer member, a movable carriage connected with said conveyer member and restrained from movement by the conveyer member when the latter is under normal tension of use, an electric motor for driving said endless conveyer, a brake co-operating with said motor, an independent brake mechanism co-operating with the conveyer, means for rendering said independent brake mechanism normally inactive, and means responsive to movement of said carriage under an abnormal condition of the conveyer member to render said independent brake mechanism active to arrest movement of said conveyer member independently of the said motor brake.

4. An escalator having in combination an endless escalator chain, upper and lower sprockets around which said chain passes, means for supporting the lower sprocket to permit rotary and linear movement thereof, including a slidable carriage in which said sprocket is journaled. a brake drum connected with the sprocket, a brake band co-operating with the brake drum, a spring for moving the carriage when chain breakage occurs, a second spring for applying the brake band to the brake drum, a latch co-operating with the last-mentioned spring to hold the brake inope 'ative during the normal operation of the escalator, and means carried by the carriage for disengaging the latch upon movement of the carriage.

5. An escalator having in combination an endless conveyer member, a movable carriage connected with said conveyer member to be restrained from movement by said conveyer member when the latter is under normal tension of use, a housing on said carriage a nut in said housing, a threaded rod engaging said nut, and a spring acting on said nut and carriage to place the conveyer member under tension.

6. An escalator having in combination an endless conveyer member, a movable carriage connected with said conveyer member and restrained from movement by the conveyer member when the latter is under normal tension of use, a brake mechanism for said conveyer member mounted on said carriage, and means for rendering the brake mechanism normally inactive, said means being actuated by movement of said carriage for rendering the brake mechanism active.

7; An escalator having in combination an endless conveyer member, a movable carriage connected with said conveyer member to be restrained from movement by said conveyer member when the latter is under normal tension of use, a spring acting on said carrier to place the conveyer member under normal tension and to automatically move said carriage when the tension on the conveyer member is reduced to a predetermined point, a brake mechanism co-opefating with the end less conveyer to arrest movement thereof, a holding device for maintaining the brake mechanism inactive with the conveyer member in its normal condition, and a device actuated by said spring for tripping said holding device with the conveyer member in an abnormal condition.

8. A11 escalator having in combination an endless conveyer chain, upper and lower s rockets over which said chain is passed, a

riving mechanism connected with said upper sprocket, a movable carriage for said lowor sprocket normally held from movement by said escalator chain when the latter is under 7 normal tension of use, a spring acting on said carriage to place the escalator chain under normal tension of use and to automatically move said carriage when the tension on said chain is reduced to a predetermined oint, and a brake mechanism for said ower sprocket normally inactive when the tension on the chain is normal and rendered active by movement of said carriage by said spring when the tension on said chain has been reducedto a given point.

In testimony whereof, I have signed my name to this specification.

Y GAD R. BARTLETT. 

